1. Technical Field
This disclosure generally relates to gas turbine engines.
2. Description of the Related Art
There are various factors that influence the operating life of gas turbine engine components. By way of example, the environment in which a gas turbine engine operates can have a significant impact. For instance, a salt-rich environment, such as experienced during transoceanic flights, can result in increased oxidation of components.
In contrast to environmental factors, other factors that influence the operating life of a gas turbine can be internal to the gas turbine. By way of example, vibrating gas turbine engine components can cause high cycle fatigue (HCF). That is, rotating components such as bearings, shafts and rotor assemblies (including gearboxes) can experience excessive frequency-related loading during periods of abnormally high vibration that tends to reduce the operating life of these components. High vibration levels are typically symptoms of a problem, whether it be damage or a design issue, and often occur over a limited rotor speed range. Some levels of vibration that produce damage are not detectable by the pilot, thus prolonging exposure to high cycle fatigue conditions that could reduce engine life. Vibration-induced HCF results in high system loads and stresses for both static and rotating engine components that could lead to premature component failures with potentially costly secondary damage (also a safety of flight issue).